Prospective, randomized comparison of effect of long-term treatment with metoprolol or carvedilol on symptoms, exercise, ejection fraction, and oxidative stress in heart failure

Comparative effects of carvedilol and metoprolol on left ventricular ejection fraction in heart failure: results of a meta-analysis

BACKGROUND

Both metoprolol and carvedilol improve cardiac function and prolong survival in patients with heart failure. Carvedilol has broader antiadrenergic effects than metoprolol, but it is not clear whether this characteristic is associated with greater benefits on cardiac function during long-term treatment.

STUDY DESIGN

We performed a meta-analysis of all 19 randomized controlled trials of carvedilol or metoprolol that measured left ventricular ejection fraction before and after an average of 8.3 +/- 0.1 months of treatment in 2184 patients with chronic heart failure. The mean daily doses were 58 +/- 1 mg of carvedilol and the equivalent of 162 +/- 1 mg of extended-release metoprolol. In the 15 placebo-controlled trials, the mean ejection fraction increased more in the trials of carvedilol than in the trials of metoprolol (placebo-corrected increases of +0.065 and +0.038, respectively), P = .0002. In the 4 active-controlled trials that compared metoprolol directly with carvedilol, the mean ejection fraction also increased more in the carvedilol groups than in the metoprolol groups (+0.084 on carvedilol and +0.057 on metoprolol, respectively), P = .009. The difference in favor of carvedilol in the active-controlled trials was nearly identical to the difference observed in the placebo-controlled trials and was apparent in patients with and without coronary artery disease.

CONCLUSION

Long-term treatment with carvedilol produces greater effects on left ventricular ejection fraction than metoprolol when both drugs are prescribed in doses similar to those that have been shown to prolong life.

Beta-blocking in heart failure patients. Balancing the evidence

Evidence for the effectiveness of beta-blockers in the management of patients with heart failure is now compelling with a database of over 13000 patients enrolled in randomised prospective placebo-controlled clinical trials. However this therapy remains vastly underused in clinical practice. The different points challenging the widespread use beta blockade agents in the routine treatment in heart failure are presented and discussed. After a review of the potential mechanism hypothesised behind the benefits of beta-blockers in heart failure, the controversial effects on the haemodynamics, exercise tolerance, hospitalisation and mortality are underlined.

[Evidence based medical treatment of heart failure]

INTRODUCTION AND OBJECTIVES

Recommendations for the treatment of heart failure were carried out by a systematic review of the available evidence of the different pharmacologic treatments.

MATERIAL AND METHODS

The review focused on the treatment of chronic and systolic heart failure. All the studies published in english about the pharmacologic treatment of heart failure where identified. The evidence of every pharmacologic treatment was classified according to: a) efficacy variables (reduction of mortality and hospitalizations, improvement of functional class, ejection fraction and exercise tolerance), and b) the level of quality of the evidence according to an evaluation scale. The evidence was also reviewed for the comparisons and the combinations of the pharmacologic treatments, as well as for the toxicity and costs of treatments.

RESULTS

The recommendations were defined according to the NYHA functional class and were classified in the A, B and C categories according to the level of quality of the available evidence. The evidence on mortality was considered the most important. First line drugs, the alternatives and other possible treatments were take into account.

CONCLUSIONS

There is enough evidence based on information about some variables such as reduction of mortality or hospitalizations to carry out treatment recommendations in all stages of heart failure. This point out the interest ant the priority of used them in the evaluation and improvement of the results of heart failure.

beta-Adrenergic and endothelin receptor interaction in dilated human cardiomyopathic myocardium

BACKGROUND

Although end-stage dilated cardiomyopathy (DCM) is characterized by defects in beta-adrenergic receptor (beta-AR) activity and increased endothelin-1 (ET-1), possible interactions between these 2 systems remain to be defined. Accordingly, the goal of this study was to determine the effects of ET receptor activation on beta-AR signaling through measurement of cyclic adenosine monophosphate (cAMP) in normal and DCM myocardium.

METHODS AND RESULTS

Myocardial sarcolemmal preparations were prepared from normal human (n = 6), dilated cardiomyopathic (n = 10), and ischemic cardiomyopathic (ICM, n = 10) tissue. Basal cAMP production was measured in the presence of ET-1 alone (10(-6) to 0(-9) mol/L) as well as after (-)isoproterenol (10(-6) to 10(-2) mol/L) or forskolin (0.05 to 30.0 micromol/L) stimulation. beta-AR and ET receptor profiles were determined by radiolabeled ligand assays. ET-1 inhibited basal cAMP production in all preparations in a concentration-dependent manner. However, beta-AR-stimulated cAMP production by either isoproterenol or forskolin was not significantly affected by ET-1. beta-AR receptor density was reduced, and a selective reduction of the ET(B) receptor occurred in both forms of DCM.

CONCLUSIONS

Under basal conditions, ET receptor stimulation reduced cAMP levels, which may influence contractility, particularly with DCM.

Carvedilol versus other beta-blockers in heart failure

Carvedilol is a beta-blocker with ancillary properties. Pilot clinical studies with carvedilol, added to the standard therapy of digoxin, diuretics and ACE inhibitors, showed beneficial effects in mild, moderate and severe heart failure. Patients consistently showed improvement in LV ejection fraction and NYHA functional class. Subsequently large clinical trials showed decreased morbidity and mortality with carvedilol in mild and moderate and more recently, severe heart failure. However, there is little or no improvement in exercise tolerance with carvedilol. The beneficial effects of carvedilol in heart failure are associated with cardiac remodelling. Metoprolol and bisoprolol are selective beta(1)-blockers without ancillary properties. Early studies showed benefits with metoprolol and bisoprolol in heart failure. Large clinical trials established that metoprolol and bisoprolol decreased mortality and morbidity in heart failure. In contrast no benefit has been shown with celiprolol, a selective beta(1)-blocker and beta(2)-stimulant in heart failure. There is a debate as to whether the ancillary properties of carvedilol contribute to its beneficial effect in heart failure, making it a better drug to use than metoprolol. Short-term studies suggested that carvedilol and metoprolol were equivalent in heart failure but short-term is probably not an appropriate way to compare the drugs. A recent long-term study and study in poor responders to metoprolol, suggest that carvedilol may be better than metoprolol in heart failure.

Carvedilol in the treatment of chronic heart failure

Along with the angiotensin-converting enzyme inhibitors (ACEIs), the beta-adrenergic receptor blockers have gradually emerged to be standard in the therapy of heart failure. Individual beta-blockers that have been shown to reduce all-cause mortality in patients with heart failure include bisoprolol, metoprolol and carvedilol. Carvedilol distinguishes from the other beta-blockers as being a non-selective beta(1)- and beta(2)-receptor blocker with (1)-receptor blockade effect and anti-oxidant properties. The drug does not have sympathomimetic activity and has vasodilatory effects attributable to its (1)-receptor blockade property. Experimental and clinical studies have confirmed carvedilol's vasodilator, anti-oxidant and anti-apoptotic properties, which may contribute to its effect in reversing cardiac remodelling in animal models and patients with heart failure. These pharmacological properties render carvedilol a potentially useful agent in the treatment of patients with heart failure. Early studies of carvedilol in heart failure have reported beneficial haemodynamic effects but variable effects on exercise tolerance and clinical well being. The large-scale US Carvedilol Heart Failure Program and the Australian/New Zealand Heart Failure Collaborative Research Group reported beneficial effects of carvedilol on mortality, morbidity and clinical well being in patients with mild-to-moderate heart failure. The recently reported but yet unpublished preliminary results of the COPERNICUS study suggest that carvedilol improves mortality and morbidity in patients with advanced heart failure and severe symptoms. At this time, it is unclear whether the ancillary pharmacological properties of carvedilol can be translated to more superior clinical benefit compared to the other beta-blockers. Preliminary studies examining surrogate end points suggest that carvedilol may improve left ventricular ejection fraction (LVEF) more than metoprolol. More conclusive information regarding their relative effects of clinical outcomes will await the completion of the COMET study, which compares the effect of metoprolol and carvedilol on mortality and morbidity, expected at the end of the year 2002.

Overview of the results of recent beta blocker trials

Results of the studies published or reported within the last 2 years provide convincing evidence that beta-blockers can decrease mortality in patients with chronic symptomatic heart failure because of left ventricular systolic dysfunction. The Cardiac Insufficiency Bisoprolol Study (CIBIS)-II and Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure (MERIT-HF) trials showed a 34% reduction in all-cause death with bisoprolol and metoprolol therapy in patients with class II-III heart failure. Data from Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS), with a 35% mortality reduction, extended this benefit to class IV patients treated with carvedilol who do not require intravenous diuretics or positive inotropes. Ongoing beta-blocker studies address new topics, such as treatment of older patients, in whom diastolic heart failure may be more common, and direct comparison of different drugs. Although the use of beta-blockers for heart failure tends to increase, implementation of the knowledge from the trials in clinical practice still remains a challenge.

Carvedilol as therapy in pediatric heart failure: an initial multicenter experience

OBJECTIVE

The objective was to determine the dosing, efficacy, and side effects of the nonselective beta-blocker carvedilol for the management of heart failure in children.

STUDY DESIGN

Carvedilol use in addition to standard medical therapy for pediatric heart failure was reviewed at 6 centers.

RESULTS

Children with dilated cardiomyopathy (80%) and congenital heart disease (20%), age 3 months to 19 years (n = 46), were treated with carvedilol. The average initial dose was 0.08 mg/kg, uptitrated over a mean of 11.3 weeks to an average maintenance dose of 0.46 mg/kg. After 3 months on carvedilol, there were improvements in modified New York Heart Association class in 67% of patients (P =.0005, chi2 analysis) and improvement in mean shortening fraction from 16.2% to 19.0% (P =.005, paired t test). Side effects, mainly dizziness, hypotension, and headache, occurred in 54% of patients but were well tolerated. Adverse outcomes (death, cardiac transplantation, and ventricular-assist device placement) occurred in 30% of patients.

CONCLUSIONS

Carvedilol as an adjunct to standard therapy for pediatric heart failure improves symptoms and left ventricular function. Side effects are common but well tolerated. Further prospective study is required to determine the effect of carvedilol on survival and to clearly define its role in pediatric heart failure therapy.

Oxidative stress and vascular damage in hypertension

Oxidative stress, a state of excessive reactive oxidative species activity, is associated with vascular disease states such as hypertension. In this review, we discuss the recent advances in the field of reactive oxidative species-mediated vascular damage in hypertension. These include the identification of redox-sensitive tyrosine kinases, the characterization of enzymatic sources of superoxide production in human blood vessels, and their relationship with vascular damage in atherosclerosis and hypertension. Finally, recent developments in the search for strategies to attenuate vascular oxidative stress are reviewed.

Are all beta-blockers the same for chronic heart failure?

beta-Adrenergic receptor blockade has been conclusively proven to increase survival and morbidity in patients with heart failure. Hospitalization rate decreases and patients feel better after receiving beta-blockers. Furthermore, this benefit is observed in a wide range of patients. The beta-blockers bisoprolol, metoprolol, and carvedilol have been extensively evaluated in heart failure patients. These drugs all show marked benefit. Bucindolol, an investigational beta-blocker, showed only mild improvement in survival in patients with heart failure. The beta-blockers differ regarding beta-selectivity, vasodilation properties, and perhaps other ancillary properties. At present, the importance and consequences of these differences are unknown.

Redox regulation of MAPK pathways and cardiac hypertrophy in adult rat cardiac myocyte

OBJECTIVES

We analyzed the regulatory function of reactive oxygen species (ROS) on the hypertrophic signaling in adult rat cardiac myocytes:

BACKGROUND

The ROS regulate mitogenic signal transduction in various cell types. In neonatal rat cardiac myocyte, antioxidants have been shown to inhibit cardiac hypertrophy, and ROS are suggested to modulate the hypertrophic signaling. However, the conclusion may not reflect the situation of mature heart, because of the different natures between neonatal and adult cardiac myocytes.

METHODS

Cultured adult rat cardiac myocytes were stimulated with endothelin-1 (ET-1) or phenylephrine (PE), and intracellular ROS levels, the activities of mitogen-activated protein kinases (MAPKs; ERK, p38, and JNK), and 3H-phenylalanine incorporation were examined. We also examined the effects of antioxidant pretreatment of myocytes on MAPK activities and cardiac hypertrophy to analyze the modulatory function of redox state on MAPK-mediated hypertrophic signaling.

RESULTS

The ROS levels in ET-1- or PE-stimulated myocytes were maximally increased at 5 min after stimulation. The origin of ROS appears to be from NADH/NADPH oxidase, because the increase in ROS was suppressed by pretreatment of myocytes with NADH/NADPH oxidase inhibitor diphenyleneiodonium. Extracellular signal-regulated kinase (ERK) activity was increased by the stimulation of ET-1 or PE. In contrast, p38 and c-Jun-N-terminal protein kinase (JNK) activities did not change after these stimulations. Antioxidant treatment of myocytes suppressed the increase in ROS and blocked ERK activation and the subsequent cardiac hypertrophy induced by these stimuli.

CONCLUSIONS

These data demonstrate that ROS mediate signal transduction of cardiac hypertrophy induced by ET-1 or PE in adult rat cardiac myocytes.

Antioxidant properties of carvedilol and metoprolol in heart failure: a double-blind randomized controlled trial

Animal and human studies have shown that carvedilol has significant antioxidant properties compared with other beta-blockers. The objective of this study was to determine if these antioxidant effects are detectable in patients with heart failure and to compare carvedilol with the selective beta-blocker metoprolol. Twenty-four patients with chronic heart failure were randomly assigned to receive either carvedilol or metoprolol in a double-blind control trial for 12 weeks in a University teaching hospital clinic. Blood pressure, heart rate, exercise tolerance, left ventricular ejection fraction, plasma total antioxidant status, erythrocyte superoxide dismutase, and glutathione peroxidase activities were determined at baseline and every 4 weeks up to 12 weeks. The results showed that erythrocyte superoxide dismutase and glutathione peroxidase were significantly reduced in carvedilol treated patients after 12 weeks of therapy, whereas metoprolol had no significant effect, although the clinical improvement over the short-term was similar with both drugs. Thus carvedilol, in addition to improving symptoms in heart failure, also possesses significant antioxidant properties. Whether this additional action influences long-term outcome is at present unknown.

Beta-blockade in heart failure: selective versus nonselective agents

Controlled clinical trials performed in more than 13 000 patients have, to date, consistently shown the beneficial effects of long term beta-adrenoceptor antagonist (beta-blocker) therapy in patients with chronic heart failure. It is not clear whether this represents a class effect or whether it is specific only to some agents. Beneficial effects on the prognosis of patients with mild to moderate heart failure have been shown with metoprolol, bisoprolol, and carvedilol. These beta-blockers, however, differ in their pharmacologic characteristics. Metoprolol and bisoprolol are selective for beta(1)-adrenergic receptors and are devoid of ancillary properties. Carvedilol, at a dosage of 50 mg/day, blocks all beta(1)-, beta(2)-, and alpha(1)-adrenergic receptors, and it has associated antiproliferative and antioxidant activities. These differences cause a varied acute hemodynamic response, with a reduction in cardiac output and a tendency toward a rise in pulmonary wedge pressure with selective agents and no change in cardiac output and a slight decrease in pulmonary pressures with carvedilol. Accordingly, when the therapy is started, the most frequent adverse effects are worsening heart failure with metoprolol and bisoprolol, and hypotension and dizziness with carvedilol. It remains controversial whether these differences also influence the long term effects of therapy. Carvedilol may provide a more comprehensive blockade of the cardiac adrenergic drive than selective beta-blockers because it does not upregulate beta(1)-adrenergic receptors, blocks all adrenergic receptors and decreases cardiac norepinephrine release. These properties may lead to a larger increase in left ventricular function and a lack of improvement in maximal exercise capacity with carvedilol, compared with selective beta-blockers. It is, however, unclear whether these differences also influence patient outcome. The long term effects of different beta-blockers on prognosis are currently being compared in the Carvedilol or Metoprolol European Trial (COMET) in which more than 3000 patients with chronic heart failure have been randomized in a 1 : 1 ratio to receive metoprolol or carvedilol.

Congestive heart failure induces endothelial cell apoptosis: protective role of carvedilol

OBJECTIVES

The purposes of this study were to determine whether the serum of patients with congestive heart failure (CHF) can induce apoptosis of endothelial cells and to elucidate the underlying mechanisms. Moreover, the effect of the beta-blocker carvedilol was investigated.

BACKGROUND

Congestive heart failure is associated with impaired endothelial function in the peripheral systemic vasculature and with systemic release of inflammatory cytokines. Pro-inflammatory cytokines have been shown to induce endothelial cell apoptosis in vitro. Therefore, we hypothesized that CHF is associated with enhanced apoptosis of endothelial cells.

METHODS

Human umbilical vein endothelial cells were exposed to the serum of patients with CHF (n = 15) or healthy volunteers (n = 11), and apoptosis was determined by fluorescence staining of the nuclei and demonstration of deoxyribonucleic acid laddering. Moreover, apoptotic membrane particles were detected in plasma samples of patients with CHF.

RESULTS

The serum of patients with CHF revealed a significantly enhanced pro-apoptotic activity as compared with age- and gender-matched healthy volunteers (p < 0.001). Furthermore, patients with CHF revealed significantly elevated plasma concentrations of apoptotic membrane particles. Apoptosis of endothelial cells correlated with elevated tumor necrosis factor-alpha (TNF-alpha) (r = 0.585, p = 0.002) and soluble TNF receptor serum levels (r = 0.517, p = 0.007). Carvedilol completely suppressed the increase in apoptosis induced by the serum of patients with CHF. Moreover, carvedilol dose-dependently inhibited TNF-alpha-induced apoptosis. The antiapoptotic activity of carvedilol was mediated by reduced activation of the caspase cascade through inhibition of mitochondrial cytochrome c release. The suppression of apoptosis by carvedilol was due to its antioxidative rather than beta-blocking effects, as the analogue BM91.0228, which has no beta-blocking activity, exerted similar effects.

CONCLUSIONS

These findings indicate that endothelial cell apoptosis may play a role in the pathophysiology of heart failure. Inhibition of endothelial cell apoptosis by carvedilol may contribute to the beneficial effects of carvedilol in patients with heart failure.

Influence of beta-blockers on mortality in chronic heart failure

OBJECTIVE

To briefly discuss the pathophysiology of heart failure and the rationale for the use of beta-blockers in the treatment of chronic heart failure. Key morbidity reduction trials are briefly mentioned, and recent mortality reduction trials are reviewed. General recommendations regarding the use of beta-blockers in heart failure are also included to guide clinical practice.

STUDY SELECTION/DATA EXTRACTION

Randomized, placebo-controlled clinical trials and meta-analyses evaluating mortality reduction with beta-blockers in the treatment of heart failure were identified using a MEDLINE search from January 1993 to March 2000. Abstracts and presented results from recent scientific meetings were also considered.

DATA SYNTHESIS

Beta-blockers have been shown to decrease hospitalization for worsening heart failure, decrease the need for heart transplant, improve New York Heart Association (NYHA) functional class, and increase left-ventricular ejection fraction. A mortality benefit has recently been demonstrated for patients with chronic heart failure. Carvedilol, bisoprolol, and controlled-release/extended-release metoprolol decreased the risk of dying by 65%, 34%, and 34%, respectively, in patients with primarily NYHA functional class II or III and systolic dysfunction. The benefit of these agents in patients with class IV heart failure or determining whether one agent has an advantage over another is being investigated in ongoing clinical trials.

CONCLUSIONS

Several beta-blockers have demonstrated mortality reduction in the treatment of patients with NYHA functional class II or III heart failure and systolic dysfunction. Beta-blockers should be considered in these patients when they are clinically stable and taking the current standard therapy of a diuretic plus an angiotensin-converting enzyme inhibitor or other vasodilator agent.

Antiremodeling effects on the left ventricle during beta-blockade with metoprolol in the treatment of chronic heart failure

OBJECTIVES

The purpose of the study was to investigate the effects of beta1-blockade on left ventricular (LV) size and function for patients with chronic heart failure.

BACKGROUND

Large-scale trials have shown that a marked decrease in mortality can be obtained by treatment of chronic heart failure with beta-adrenergic blocking agents. Possible mechanisms behind this effect remain yet to be fully elucidated, and previous studies have presented insignificant results regarding suspected LV antiremodeling effects.

METHODS

In this randomized, placebo-controlled and double-blind substudy to the Metoprolol CR/XL Randomized Intervention Trial in Heart Failure (MERIT-HF), 41 patients were examined with magnetic resonance imaging three times in a six-month period, assessing LV dimensions and function.

RESULTS

Decreases in both LV end-diastolic volume index (150 ml/m2 at baseline to 126 ml/m2 after six months, p = 0.007) and LV end-systolic volume index (107 ml/m2 to 81 ml/m2, p = 0.001) were found, whereas LV ejection fraction increased in the metoprolol CR/XL group (29% to 37%, p = 0.005). No significant changes were seen in the placebo group regarding these variables. Left ventricular stroke volume index remained unchanged, whereas LV mass index decreased in both groups (175 g/m2 to 160 g/m2 in the placebo group [p = 0.005] and 179 g/m2 to 164 g/m2 in the metoprolol CR/XL group [p = 0.011).

CONCLUSIONS

This study is the first randomized study to demonstrate that the beta1-blocker metoprolol CR/XL has antiremodeling effects on the LV in patients with chronic heart failure and consequently provides an explanation for the highly significant decrease in mortality from worsening heart failure found in the MERIT-HF trial.

Role of beta blockers in congestive heart failure

Prolonged activation of the adrenergic nervous system has adverse consequences on the cardiovascular system in patients with congestive heart failure. Beta adrenergic receptor-blocker therapy modifies these deleterious effects. Beta blockers have been shown to improve myocardial function and survival when used in conjunction with conventional treatment with diuretics, angiotensin-converting enzyme inhibitors, and digoxin. Beta blocker therapy in mild-to-moderate heart failure should not be delayed because it causes some reversal of both neurohormonal compensatory mechanisms and the deleterious myocardial remodeling process. This paper reviews the beneficial effects of beta adrenergic receptor-blocker therapy on the pathophysiology, symptoms, left ventricular function, morbidity, and mortality in patients with congestive heart failure. (c)2000 by CHF, Inc.

Metoprolol: a review of its use in chronic heart failure

Metoprolol, a relatively selective beta1-blocker, is devoid of intrinsic sympathomimetic activity and possesses weak membrane stabilising activity. The drug has an established role in the management of essential hypertension and angina pectoris, and more recently, in patients with chronic heart failure. The effects of metoprolol controlled-release/extended-release (CR/XL) in patients with stable, predominantly mild to moderate (NYHA functional class II to III) chronic heart failure have been evaluated in the large Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure (MERIT-HF) trial and the much smaller Randomized Evaluation of Strategies for Left Ventricular Dysfunction (RESOLVD) pilot study. Treatment with metoprolol CR/XL was initiated at a low dosage of 12.5 to 25 mg once daily and gradually increased at 2-weekly intervals until the target dosage (200 mg once daily) or maximal tolerated dosage had been attained in patients receiving standard therapy for heart failure. At 12 months, metoprolol CR/XL was associated with a 34% reduction in relative risk of all-cause mortality in patients with chronic heart failure due to ischaemic or dilated cardiomyopathy in the MERIT-HF trial. The incidence of sudden death and death due to progressive heart failure were both significantly decreased with metoprolol CR/XL. Similarly, a trend towards decreased mortality in the metoprolol CR/XL group compared with placebo was observed in the RESOLVD trial. Data from small numbers of patients with severe (NYHA functional class IV) heart failure indicate that metoprolol CR/XL is effective in this subset of patients. However, no firm conclusions can yet be drawn. Improvement from baseline values in NYHA functional class, exercise capacity and some measures of quality of life with metoprolol CR/XL or immediate-release metoprolol were significantly greater than those with placebo. The drug is well tolerated when treatment is initiated in low dosages and gradually increased at intervals of 1 to 2 weeks.

CONCLUSIONS

Metoprolol CR/XL effectively decreases mortality and improves clinical status in patients with stable mild to moderate (NYHA functional class II or III) chronic heart failure due to left ventricular systolic dysfunction, and the drug is effective in patients with ischaemic or dilated cardiomyopathy. Although limited data indicate that metoprolol CR/XL is effective in patients with severe (NYHA functional class IV) chronic heart failure, more data are needed to confirm these findings. Treatment with metoprolol CR/XL significantly reduced the incidence of sudden death and death due to progressive heart failure.

A comparison of carvedilol and metoprolol antioxidant activities in vitro

Carvedilol is a vasodilating beta-blocker and antioxidant approved for treatment of mild to moderate hypertension. angina, and congestive heart failure. Metoprolol is a beta1-selective adrenoceptor antagonist. When carvedilol and metoprolol were recently compared in clinical trials for heart failure, each showed beneficial beta-blocker effects such as improved symptoms, quality of life, exercise tolerance, and ejection fraction, with no between-group differences. When thiobarbituric acid reactive substance (TBARS) levels were measured in serum as an indirect marker of free radical activity, there were also no between-group differences. However, we had noted superior cardioprotection by carvedilol in comparison to metoprolol in ischemia and reperfusion models. We therefore examined antioxidant activity directly in cells and tissues. Here we show that in cultured rat cerebellar neurons, and in brain and heart membranes, carvedilol has far greater antioxidant activity than metoprolol, which is essentially inactive as an antioxidant in these model systems. The antioxidant activity of carvedilol could be explained by a greater degree of lipophilicity, as measured by its ClogP value of 3.841 as contrasted to a ClogP value of 1.346 for metoprolol. Alternatively, the molecular structure of carvedilol favors redox recycling, which the structure of metoprolol does not. Therefore, carvedilol could have additional pharmacologic effects that are favorable for long-term therapy.

Pharmacotherapy of systolic heart failure: a review of recent literature and practical applications

Since the publication of the Agency for Health Care Policy and Research Guidelines for treatment of heart failure, a number of new agents have been investigated for this indication. beta-Blockers have now been shown to improve outcomes in mild to moderate heart failure when added to standard therapy. Angiotensin II receptor antagonists have also been investigated and show promise. In general, calcium channel blockers are second- or third-line agents in patients refractory to other therapy. Investigational agents including spironolactone may also hold promise for future therapy.

The effect of beta-blockers on health-related quality of life in patients with heart failure

Beta-blockers reduce the risk of death in patients with heart failure and are recommended in those with stable class II or III disease despite optimal standard therapy. Health-related quality of life (HRQOL) is an increasingly important end point in clinical trials. We reviewed all studies that determined the effect of beta-blockers on HRQOL in patients with heart failure. In these trials, HRQOL was assessed by the Quality of Life Questionnaire in Severe Heart Failure and the Minnesota Living with Heart Failure Questionnaire. Three of the 10 studies that used either of these instruments reported significant improvements in scores. When HRQOL was determined by a single-question global assessment, substantial improvements were observed by patients and physicians in five of the seven studies that used the instrument. Possible reasons for the lack of consistent effect on HRQOL include lack of responsiveness of currently available instruments, incomplete data collection, and true lack of effect of beta-blockers on HRQOL in these patients.

MIC trial: metoprolol in patients with mild to moderate heart failure: effects on ventricular function and cardiopulmonary exercise testing

Beta-blocker therapy results in a functional benefit in patients with heart failure (CHF) due to idiopathic dilated cardiomyopathy (DCM). This study assessed if similar effects were observed in patients with ischemic heart disease (CAD), NYHA II-III after 6 months of therapy with metoprolol.

METHODS AND RESULTS

Fifty-two patients with CHF secondary to DCM (26 patients) and CAD (26 patients) and a left ventricular ejection fraction (EF)<40% were enrolled in the placebo-controlled study. The study medication was titrated over 6 weeks, the mean final dosage was 135 mg/day. Three patients died due to cardiogenic shock, two received placebo and one metoprolol. Eight patients did not complete the study due to non-compliance. Metoprolol significantly reduced heart rate at rest and after submaximal and maximal exercise. Vo(2)-max and Vo(2)-AT as well as the 6-min walk test improved significantly after metoprolol treatment. There was a significant increase in EF at rest (27.3-35. 2%), submaximal (28.5-37.7%) and maximal exercise (28.7-40.9%) in the metoprolol-treated patients. No differences were found between patients with CAD and DCM. We also observed reduced left ventricular volumes.

CONCLUSION

The additional therapy with metoprolol improved cardiac function and the cardiopulmonary exercise capacity in patients with CHF.

Deactivation of the sympathetic nervous system in patients with chronic congestive heart failure

In this article, we review the basic biology, signal transduction pathways, and clinical pharmacology associated with cardiac beta-adrenergic receptors (beta-ARs) in the context of the use of beta-blocking agents in patients with chronic congestive heart failure. Adrenergic receptors, particularly the beta-AR subtypes (beta(1)-AR and beta(2)-AR), are known to play a critical role in the modulation of cardiac function, providing for both "adaptive" and "maladaptive" compensatory changes. In the context of exercise or self-preservation, the adrenergic nervous system, acting via beta-ARs permits an appropriately rapid, highly-dynamic increase in cardiac function. Conversely, in individuals with chronic congestive heart failure, the sustained, heightened activation of adrenergic nervous system, as manifested by increases in circulating catecholamines, results in down- regulation and desensitization of myocardial beta-ARs, and potentially, significant myocardial damage. A number of recent clinical trials have demonstrated a marked mortality benefit from using beta-blocking agents such as metoprolol and carvedilol in patients with heart failure. The pharmacologic properties of several of these drugs and some of the specifics of their usefulness and limitations are discussed herein.

Selective or nonselective beta-adrenergic blockade in patients with congestive heart failure

Controlled clinical trials, performed in more than 13,000 patients, have consistently shown the beneficial effects of long-term beta-blocker therapy in patients with chronic heart failure. However, it is not clear whether this is a class effect or if it is specific only for some agents. Beneficial effects on the prognosis of the patients with mild to moderate heart failure have been obtained with metoprolol, bisoprolol, and carvedilol. Metoprolol and bisoprolol are selective for beta(1)-receptors and without ancillary properties, carvedilol, at doses of 25 mg twice daily, blocks beta(1)-, beta(2)-, and a(1)-adrenergic receptors, and has associated antiproliferative and antioxidant activities. These differences are important for the acute hemodynamic effects, but it is still controversial whether they may also influence the long-term effects of therapy. Differently from selective b-blockers, carvedilol blocks all adrenergic receptors, does not upregulate beta1-receptors, decreases cardiac norepinephrine release, and has associated antioxidant effects. These differences may cause a larger increase in left ventricular function, which was significant in some, but not all of the direct comparisons of the two agents. The long-term effects of different beta-blockers on prognosis are currently compared in the Carvedilol or Metoprolol European Trial, in which more than 3000 patients with chronic heart failure have been 1:1 randomized to metoprolol or carvedilol and are going to be followed for more than 2 years.

Are all beta blockers the same for heart failure?

Based on impressive morbidity and mortality data using beta blockers in heart failure, this therapy has now become part of the standard of care for patients with New York Heart Association II/III symptoms. The question remains whether there are clinically relevant differences between the beta blockers that have shown beneficial effects. This review summarizes the major mortality trials, and examines the smaller comparative trials of second and third generation beta blockers.

A rationale for the use of beta-blockers as standard treatment for heart failure

BACKGROUND

Cardiac sympathetic activation is one of the major and earlier changes observed in patients with heart failure. Its relation to the severity of the disease and its independent prognostic value show that it may directly contribute to the progression of heart failure. beta-Blockers are the most effective tool to counteract the untoward effects of sympathetic activation on the cardiovascular system.

METHODS AND RESULTS

We reviewed the results of the placebo-controlled, double-blind studies about the effects of beta-blockers in patients with heart failure. These studies have involved almost 10,000 patients to date and have consistently shown that the long-term administration of beta-blockers is associated with a highly significant improvement in both left ventricular function and prognosis of the patients with heart failure. The evidence supporting the use of beta-blockers now equals or even surpasses that of angiotensin-converting enzyme inhibitors; therefore beta-blockers should be considered part of standard therapy. Issues that remain unclarified include the mechanisms through which beta-blockers may improve cardiac function and their tolerability and efficacy in specific groups of patients (such as those with asymptomatic left ventricular dysfunction, severe heart failure, the elderly, or those with left ventricular diastolic dysfunction). It is not currently clear whether the pharmacologic differences between individual beta-blockers are clinically relevant. If they are, the potential for even greater benefit with certain agents exists. It is hoped that these issues will be clarified by the results of ongoing multicenter trials.

Cardiac remodeling--concepts and clinical implications: a consensus paper from an international forum on cardiac remodeling. Behalf of an International Forum on Cardiac Remodeling

Cardiac remodeling is generally accepted as a determinant of the clinical course of heart failure (HF). Defined as genome expression resulting in molecular, cellular and interstitial changes and manifested clinically as changes in size, shape and function of the heart resulting from cardiac load or injury, cardiac remodeling is influenced by hemodynamic load, neurohormonal activation and other factors still under investigation. Although patients with major remodeling demonstrate progressive worsening of cardiac function, slowing or reversing remodeling has only recently become a goal of HF therapy. Mechanisms other than remodeling can also influence the course of heart disease, and disease progression may occur in other ways in the absence of cardiac remodeling. Left ventricular end-diastolic and end-systolic volume and ejection fraction data provide support for the beneficial effects of therapeutic agents such as angiotensin-converting enzyme (ACE) inhibitors and beta-adrenergic blocking agents on the remodeling process. These agents also provide benefits in terms of morbidity and mortality. Although measurement of ejection fraction can reliably guide initiation of treatment in HF, opinions differ regarding the value of ejection fraction data in guiding ongoing therapy. The role of echocardiography or radionuclide imaging in the management and monitoring of HF is as yet unclear. To fully appreciate the potential benefits of HF therapies, clinicians should understand the relationship between remodeling and HF progression. Their patients may then, in turn, acquire an improved understanding of their disease and the treatments they are given.

Improvement in left ventricular function in response to carvedilol is accompanied by attenuation of neurohumoral activation in patients with dilated cardiomyopathy

BACKGROUND

We sought to evaluate whether improvement in ejection fraction (EF) with carvedilol therapy is accompanied by improvement in neurohumoral factors.

METHODS AND RESULTS

Forty-two patients with dilated cardiomyopathy were given carvedilol for 3 to 5 months. Changes in EF, plasma atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and norepinephrine levels were determined. Iodine-123 metaiodobenzylguanidine (MIBG) images were also obtained before and after carvedilol therapy. Myocardial uptake of MIBG was calculated as the heart to mediastinal activity ratio (H/M). Storage and release of MIBG was calculated as percent myocardial MIBG washout rate (WR). We divided patients into 2 groups: 27 responders whose EF increased by more than 5% and 15 nonresponders whose EF increased by 5% or less. EF of responders increased by 15 +/- 5% and that of nonresponders by 1 +/- 4%. Although MIBG image-derived indexes of nonresponders remained unchanged, the delayed H/M (1.91 +/- 0.34 v 2.24 +/- 0.53, P < .01) and WR (49 +/- 11 v 39 +/- 9%, P < .01) of responders improved, respectively. The plasma ANP (51 +/- 50 v 27 +/- 24 pg/mL, P < .01) and BNP (194 +/- 197 v 49 +/- 62 pg/mL, P < .01) levels of responders decreased. The degree of changes in the plasma BNP level correlated with changes in EF (r = -.698, P < .01).

CONCLUSION

The improvement in EF with carvedilol therapy was proved to be accompanied by an improvement in neurohumoral factors.

Beta-blockers and spironolactone in heart failure

Neurohormonal antagonism is now recognized as an essential treatment modality for heart failure. As a prime example, the benefits of blocking the renin-angiotensin system with angiotensin converting enzyme inhibitors are clearly established for all four New York Heart Association classes. In this clinical trials review, we discuss two other therapies with neurohormonal targets: beta-blockers and the sympathetic nervous system, and the aldosterone antagonist spironolactone.

Arrhythmias in heart failure: current concepts of mechanisms and therapy

About one half of deaths in patients with heart failure are sudden, mostly due to ventricular tachycardia (VT) degenerating to ventricular fibrillation or immediate ventricular fibrillation. In severe heart failure, sudden cardiac death also may occur due to bradyarrhythmias. Other dysrhythmias complicating heart failure include atrial and ventricular extrasystoles, atrial fibrillation (AF), and sustained and nonsustained ventricular tachyarrhythmias. The exact mechanism of the increased vulnerability to arrhythmias is not known. Depending on the etiology of heart failure, different preconditions, including ischemia or structural alterations such as fibrosis or myocardial scarring, may be prominent. Reentrant mechanisms around scar tissue, afterdepolarizations, and triggered activity due to changes in calcium metabolism significantly contribute to arrhythmogenesis. Furthermore, alterations in potassium currents leading to action potential prolongation and an increase in dispersion of repolarization play a significant role. Treatment of arrhythmias is necessary either because patients are symptomatic or to reduce the risk for sudden cardiac death. The individual history, left ventricular function, electrophysiologic testing, and the signal-averaged ECG give useful information for identifying patients at risk for sudden cardiac death. The implantable cardioverter defibrillator (ICD) has evolved as a promising therapy for life-threatening arrhythmias. A potential role may exist for antiarrhythmic drugs, mainly amiodarone. There is growing evidence that patients with sustained VT or a history of resuscitation have the best outcome with ICD therapy regardless of the degree of heart failure. Many of these patients require additional antiarrhythmic therapy because of AF or nonsustained VTs that may activate the device. Catheter ablation or map-guided endocardial resection are additional options in selected patients but seldom represent the only therapeutic strategy.

New advances in the pharmacological management of chronic heart failure

The management of heart failure has evolved in parallel with advances in the understanding of the disease process. Inotropes and diuretics are used to combat pump failure and fluid overload. While no convincing data has emerged regarding the long-term safety of inotropes, new exciting data concerning the role of diuretics, especially aldactone, has led to a renewed interest in this class of drug therapy. Angiotensin converting enzyme inhibitors (ACE inhibitors) were noted to not only affect symptomatology but also decrease mortality by interfering with the renin-angiotensin-aldosterone system. Recent research has focused on more complete blockade of the renin-angiotensin system than that achieved with ACE inhibitors alone with the addition of direct angiotensin II receptor blockers. This new class of drugs may become not only a reasonable alternative to ACE inhibitors in patients intolerant of the drug but also a possible addition to ACE inhibitors in the battle to prevent progression of remodelling and disease. beta-blockers are the most exciting new class of drugs used to combat heart failure. They appear not only to combat the remodelling process that occurs in the progression of disease but also other pathological events such as apoptosis and cellular oxidation. New medical therapies currently being investigated include novel agents such as endothelin antagonists, natriuretic peptides, vasopressin antagonists and anticytokine agents--all part of a new era in drug management of heart failure that has evolved with continued advances in the understanding of chronic heart failure (CHF).

beta-Blockers in congestive heart failure

Recent advances in the understanding of the basic mechanisms underlying congestive heart failure (CHF) have focused on the role of neurohormonal activation. Chronic adrenergic overstimulation is directly toxic to myocardial cells, impairs function, causes peripheral vasoconstriction and may induce programmed cell death via apoptosis. beta-Adrenergic blockade can interrupt this pathological process. Accumulating evidence now points to a clear role for beta-blocking agents in the management of heart failure, reducing both the morbidity and mortality associated with CHF. This report will review the recent clinical trials supporting the use of beta-blockers in CHF, briefly highlight some practical considerations in the use of these drugs in patients with CHF and discuss several areas of controversy in which further study is needed.

Anti-oxidant therapy for the treatment of coronary artery disease

Coronary artery disease is the most common cause of death in developed countries. It may present in many different ways, but most frequently as a myocardial infarction, sudden death, angina or heart failure. Preventive measures in relation to coronary artery disease are particularly important because of its high incidence, high mortality and because most patients die outside hospital. Since the oxidation of low density lipoprotein cholesterol (LDL-C) is a critical early step in the process of atheroma formation, taking anti-oxidants to prevent LDL-C oxidation may prove a very effective means of reducing coronary artery disease mortality. However, the role of anti-oxidants in coronary artery disease prevention needs to be evaluated as part of an overall strategy that includes pharmacological and non-pharmacological measures, which are described in this review. In addition, a more structured and scientific approach to anti-oxidant therapy needs to be adopted. This requires that evidence for oxidative stress in a particular condition is obtained, the nature and severity determined and an appropriate anti-oxidant is administered, in an effective dose, which can be shown to correct the oxidative stress. When this is achieved, meaningful clinical trials should be possible, which will determine the place of anti-oxidant therapy for the specified condition.

Clinical Pharmacology of Carvedilol

BACKGROUND: There is now a wealth of data supporting the use of beta-blockers in heart failure and the additional pharmacological properties of carvedilol are thought to play an important role in the therapeutic efficacy of carvedilol in this disease. METHODS AND RESULTS: Carvedilol is licensed for the treatment of essential hypertension, chronic stable angina, and mild to moderate chronic heart failure. This article provides an up-to-date review of the clinical pharmacology of carvedilol, with particular emphasis on its clinical effects in heart failure. CONCLUSION: Carvedilol is a multiple-action neurohormonal antagonist that offers nonselective beta-blockade, alpha-1 blockade, antioxidant, anti-ischemic mortality, and anti-proliferative properties. In addition to reductions in hospitalization and mortality rates, benefits of carvedilol in heart failure include dramatic improvements in left ventricular function and other parameters of cardiac remodeling.